Percussion fuse



c. DEL PRATO 2,359,752

PERCUSSION FUSE Filed July 20, 1940 Patented Oct. 10, 1944 PERCUSSION FUSE Application July 20, 1940, Serial No. 346,639 In Italy August 31, 1939 2 Claims.

This invention relates to percussion fuses, more particularly for use in rifled firearms of the artillery type.

This invention has utility when employed in connection with fuses which generate sufiicient centrifugal force in flight to cause its various parts to release the safety features thereof so it may cause explosion of its carrying shell upon impact.

Referring to the drawing:

Fig. 1 is an axial section through the fuse; and

Fig. 2 is an axial section through the fuse on a plane perpendicular to the showing in Fig. 1.

The fuse comprises a cup-shaped body I of suitable contour and exteriorly threaded for mounting in a projectile or shell. This body is provided with a head and an open end through which the fire may pass when generated within the fuse to set off the contents of its carrying shell.

Mounted within the body I on bearings 6, 23, is rotatable cage 5, which is restrained from axial shifting by bearings 3 at its inner end and by nose 24 at its outer end abutting against the head portion.

Axially extending from the inner end of the cage 5 is cylindrical cavity 1 having an enlarged inner peripheral chamber IS a little more than half the distance toward the head. The chamber 55 is provided with a wall tapering downwardly toward the head then radially to a relatively small fire conduit 22 leading to a radially extending chamber 2|.

The conduit 22 continues from the opposite side of the chamber to communicate with branches is, which in turn extend to ducts l'l leading to the open end of the body I. Between the ducts I9, I? are chambers which may be filled with cylindrical powder charges I8.

Mounted in the cavity is cylindrical primer carrier member H having a seat intermediate its length carrying the detonator, or percussioncup. A duct continuation from the seat extends slightly into a plug 20 in the chamber 2!, which is held in duct capping position as a safety means until the fuse is used for its intended purpose. This plug 20 prevents any premature fire from the percussion-cap reaching the ducts I9 and the powder charges l8.

The opposite end of the cavity is sealed by a plug which mounts the firing pin 10 axially of the fuse and normally spaced from the percussion-cap.

Additional safety means are employed in the form of a lock to maintain the parts, as shown in the drawing. To this end there is provided a plurality of sockets parallel to and spaced from the fuse axis and a radial opening intersecting the sockets and in alignment with an opening through the pin carrying plug. In this latter opening there is disposed a ball 8 oppositely abutted by a pair of cylinders 9 whose opposite termini are at the wall of the sockets. In the sockets are disposed pins [3 in abutment with the cylinders 9. The pins are held in cylinder locking position by springs M. The pins are restrained in the sockets by plugs 4.

An enveloping sheath I2 encloses the cage 5 thereby preventing the safety member from leaving the cage and interfering with the normal operation.

When the shell carrying the fuse travels through the air in a rotating manner, the body I, of course, rotates with the shell, while there is a lag to the rotation of the cage. This provides a time interval before the safety locks operate insuring against premature ignition in flight.

The cycle of operation begins with the pins [3, whose mass or inertia is sufficient to move against the resistance of the springs 14, out of contact with the cylinders 9. Then when the cage has reached a sufficient speed of rotation, the centrifugal force causes the cylinders to move outwardly and away from contact with the firingpin plug and the percussion-cap carrying member H, which is now free to move. Balls 16, between this member and the tapered cam face of chamber I5 moving outwardly, urge the member II toward the firing pin, thereby withdrawing the extension of member II from plug 20. This plug is then centrifugally moved to uncover the duct extension.

With the parts in this position, the striking of the shell against its objective causes the percussion-cap to strike the firing-pin to be ignited and the fire passes from member H, through chamber 2|, conduit 22, and ducts I9 to ignite the powder charges [8, the flame from which travels through ducts l1 into the shell, thereby performing its function.

What I claim is:

1. A percussion fuse for rotatable projectiles comprising, a casing adapted to be secured to a projectile and having a cylindrical cavity therein arranged axially of the projectile, a body member rotatably mounted in said cylindrical cavity, a cap carrier slidably mounted in said body member, said body member having a passage therein terminating adjacent said cap carrier; a block radially movable in said body memher, means carried by the cap carrier retaining said block in a position to close said passage, a firing pin carried by said body member extending towards said cap carrier, a. radially slidable lug engaging said cap carrier and said body member preventing sliding movement of the cap carrier towards said firing pin, a pin of considerable mass slidable rearwardly in said body member upon forward. acceleration of the projectile releasing said lug for radial outward movement upon rotation of the projectile, balls movable radially out- 7 ward upon rotation of the projectile for moving the cap carrier forwardly to release said block for radial movement to a position to open said passage whereby the cap carrier may slide forwardly in the body member upon impact of the projectile to engage said firing pin and discharge the cap through said passage.

2. In a percussion fuse for rotatable projectiles shell.

comprising, a casing adapted to be secured to a projectile and having a cylindrical cavity therein arranged axially of the projectile, a cage rotatrably mounted in said cavity, a cap carrier slidably mounted in said cage, said cage having a passage therein terminating adjacent said cap carrier, a block radially movable in said cage, means carried by said cap carrier retaining said block in a position to close said passage and releasable on forward movement ofsaid cap carrier to open said passage, means retaining said cap carrieragainst forward movement and movable on rotary movement of said cage to release said cap carrier,.and inertia means for retaining said last named means and movable to release said last named means on acceleration of'said CESARE DEL PRATO. 

